Multiple relationships between rate of oxidative phosphorylation and Δµ̃H in rat liver mitochondria

Abstract

The relationship between rate of ATP synthesis and transmembrane electrochemical proton gradient has been determined in rat liver mitochondria oxidizing succinate, using the respiratory inhibitor malonate or the uncoupler FCCP to decrease Aj?H progressively. As previously reported [(1982

Bioenergetic consequences of accumulating the common 4977‐bp mitochondrial DNA deletion

“…Second, the decrease in ATP synthesis may be partially due to specific defects in the F 0 F 1 -ATP synthase, in addition to effects on membrane potential. Third, the dependence of ATP synthesis on mitochondrial membrane potential is complex, being negligible below a threshold value of 110Ϫ 130 mV, and with a steep dependence on membrane potential above this value [50,51]. Consequently, minor changes in membrane potential could have a disproportionately large effect on ATP synthesis.…”

“…The Ph 3MeP ϩ accumulation ratio decreased from 53 at rest to about 22 in the 143B cells during ATP synthesis, corresponding to a 25Ϫ30-mV decrease in membrane potential (Figs 3 and 6). To determine how the ATP synthesis rate depended on mitochondrial membrane potential, various amounts of malonate, a competitive inhibitor of succinate dehydrogenase, were used to generate a series of membrane potentials and consequent ATP synthesis rates [50,51]. The rate of ATP synthesis as a function of the Ph 3 MeP ϩ accumulation ratio is shown in Fig.…”

The dependence of the rate of transhydrogenase on the value of the protonmotive force in chromatophores from photosynthetic bacteria

“…FCCP, carbonyl cyanide ptrifluoromethoxyphenylhydrazone; A~, bulk phase electric potential difference across the chromatophore membrane; ApH, bulk phase pH gradient across the chromatophore membrane; Ap, protonmotive force; Jl, rate of the pyridine nucleotide transhydrogenase systematic experimental errors might distort the true relationship (see [1,4,6]). Alternatively different biological systems might behave in different ways -some showing a greater, others showing a lesser tendency towards delocalisation of the highenergy intermediate [6].…”

“…Alternatively different biological systems might behave in different ways -some showing a greater, others showing a lesser tendency towards delocalisation of the highenergy intermediate [6].…”

“…Some observations suggest that the relationship is unique [1][2][3][4], others that it is influenced by the agent used to lower Ap [5][6][7][8][9]. The latter result calls for refinements of the chemiosmotic hypothesis of energy coupling between electron transport and ATP synthesis (e.g.…”